Calculation Of Horizontal Displacement Of The Excavation With Soil Nailing

With the rapid development of China’s national economy and the rapid expansion of urbanization, swelling urban population, the expanding urban population, land resources become increasingly tense. building toward a higher and deeper two directions. Therefore, high-rise buildings and underground space development is increasing. Accordong to the characteristics of city construction and the actual situation that high-rise buildings and deep foundation pit engineering has just started in Yinchuan, this paper takes the actual condition of deep foundation pit engineering of Wanda Plaza and the international conference center of Ningxia as the study target, the analysis of pit horizontal displacement after foundation pit excavation has been made as the research contents, different form spit of pit horizontal displacement by use two theoretical calculations method and FEM based on analyzing the information of subject survey, design and construction. Then, the calculating data were compared with the site survey data, finally analyze and summarize the three methods. The chief research contents and achievement as follow:(1) Based on a lot of reading relevant literatures, the mechanism of the machanism of the foundation pit deformation, the deformation analysis method and pit horizontal displacement of soil calculation method after supporting were discussed. Pit horizontal displacement by use two theoretical calculations method and FEM were proposed.(2) Semi-infinite elastic body displacement calculation of analytical formuls and the incremental force of soil nail during the construction. A new phenomenological model for the analysis of soil nailing during the excavation is established. The pit grading excavation of earth pressure reduction wes analyzed. Selected two practical works of the region as a research target, pit horizontal displacement by use formula and Analysis model, design and construction. Then, the calculating data were compared with the site survey data,(3)2-D finite element analysis method about deep foundation pit excavation were described; the initial stress field and displacement field before foundation pit excavated was analyzed; the features and adaptability of basal constitutive model (Mohr-Coulomb elastic plastic model which is the base of foundation pit simulation) were discussed.(4) The numerical model of foundation pit excavation was established based on the PLAXIS2D. The calculated boundary conditions,computing unit and parameters were determined with practical engineering; the computational model was built, and specific process of numerical simulation in solving actual foundation pit excavation was given. The reliability and usefulness of the model were verified by actual monitoring data in process of foundation construction.(5) The numerical simulation for excavation of foundation pit was carried out under the supporting condition; horizontal displacement during excavating foundation pit by steps, and total displacement of foundation pit support after. Analysis showed that horizontal displacement and soil sedimentation of foundation pit increased with excavation depth rising; the pit excavation pit wall horizontal displacement in mutations increases.(6) According to the analysis of the region’s engineering examples, drawn the three pit wall horizontal displacement calculation method applicability and excellent point slightly, pointed out that different methods of calculation can be applied according to the different stages of the actual project.